There is a significant amount of pressure to improve a building’s energy efficiency performance. This is achieved through techniques and sustainable products that support energy efficiency and conservation. Cost-efficiency is key here, and one of the best ways to achieve this is to install the correct thermal insulation. In doing so, one ensures the building performs as required throughout its lifespan and in turn decreases cost in energy usage.
Often the question is asked, why spend money upfront for the cost of insulation? The answer is simple – it results in reduced energy costs as heat is retained in the winter and it reduces the need for cooling in the summer. In turn, smaller mechanical ventilation systems need to be installed, if at all, pending on the design of the building, adding to additional cost saving.
We spoke with three industry experts to identify the top five tips one should consider when specifying insulation.
Des Schnetler, TIPSASA chairperson
When selecting thermal insulation, ensure that the material:
- Is in compliance with relevant South African National Standards (SANS), i.e. product standards.
- Is appropriate for the intended occupancy class in accordance with SANS 10400 Part A.
- Complies with the fire-safety requirements given in SANS 10400 Part T and SANS 428.
- Complies with the recommended R-value for the relevant climatic zones in accordance with SANS 10400 Part XA.
Schnetler also offered the following input that should be considered:
a. The Energy Efficiency Regulation is applicable to all new buildings and extensions and include the compulsory insulation of thermal insulation in certain occupancy classes, since 2011.
b. The SABS developed energy-efficiency standards, namely SANS 10400 Part XA: Energy usage in buildings, to assist the construction industry, to achieve Governments goals to save energy.
What is thermal insulation?
Thermal insulation is the material that is used to reduce the rate of heat transfer through external surfaces in a home or building. Basically, when you insulate your building you are wrapping it in a “protective blanket” which reduces the transfer of heat into and out of the building.
In the winter it reduces the rate at which heat is lost from a building, and in the summer it reduces the rate of heat entry into the building.
Top tips when considering R-value
a. Insulation materials are rated for their performance in restricting heat transfer. This is expressed as the R-value, also known as thermal resistance.
b. The R-value is a guide to its performance as an insulator – the higher the R-value, the better the insulation (i.e. resistance to heat flow) it provides.
c. Use the nominal R-values as listed by the manufacturer on the packaging of the thermal resistance to determine performance.
d. Products which have the same R-value will provide the same insulating effect as each other, provided they are correctly installed.
e. The higher the R-value, the more effective the insulation.
f. The information available on the product data sheet and/or label must include the R-value and fire performance classification.
g. Products must be installed in accordance with the manufacturer’s installation specifications.
Christopher Knight, sales and marketing, Western Cape, at Rigifoam
- Analyse what you want out of the insulation. Has a rational design been taken into consideration? (Is it thermal or acoustic?)
- What is the application? Each insulation has its own application limitations (over purlin, nail-up ceiling, over truss, cavity wall etc.).
- What is the life expectancy of the insulation?
- Does the insulation require an aesthetic appeal?
- Does the insulation supply the correct R-value required for the “deemed to satisfy” energy efficiency in terms of the SANS 10400 XA?
- Brochure value vs Application Value – Is the thermal performance (R-Value) the same when used in application? Most insulation materials fall well short when installed in a building.
Further tips and background information from Knight
a. Thermal insulation is the reduction of heat transfer between objects in thermal contact or in range of radiative influence. In turn, soundproofing or acoustics is any means of reducing the sound pressure with respect to a specified sound source and receptor. Soundproofing can reduce the transmission of unwanted direct sound waves from the source to an involuntary listener using distance and intervening objects in the sound path.
b. In terms of life expectancy, you need to look at how long the building is going to be in existence before an upgrade is planned (shopping centres, for instance). Roof sheeting, for example, can offer roughly 20 years. You need to ensure that the insulation will outlast, or at least match, this figure.
c. Insulation must meet the minimum requirements in terms of the Energy Zone Map. This will reduce the heating, ventilation and air-conditioning (HVAC) that will reduce the influence on the environment and energy consumption.
Ben de Freitas, Commercial and Technical Consultant, at Isover
- A correctly designed and insulated light weight wall system will offer the same or better thermal properties than a conventional brick and mortar construction.
- In a world where a combination of efficient buildings, sustainability and minimising utility costs is a hot topic, industry still makes the mistake of believing that insulation is a one-size-fits-all approach.
- Select a well-known insulation brand which will meet the technical requirements of the residential, non-residential and technical markets. There are various insulation product types to suit a wide range of applications such as metal buildings, walls, ceilings, floors and HVAC systems, all of which perform best when optimally installed.
- Since the publications of SANS 10400-XA in 2011, there has been numerous claims pertaining to performance of different insulation materials. One should consider sound scientific data and holistic view before making a final decision on the insulation materials to use. Let’s take an example of reflective paints vs bulk insulation. Bulk Insulation prevents the transfer of heat through conduction and convection, using pockets of trapped air. The foils facing on bulk insulation does contribute towards reducing radiation heat transfer, whereas radiant paints only protect from radiation heat transfer. They reflect suns radiation. So may be somewhat effective in summer but because thermal paints do not prevent transfer of heat, they are not effective in preventing heat loss in winter.
- Always consider fire safety when specifying insulation for specific building types. Choose insulation materials that adhere to the local fire regulations, better still, choose materials that are non-combustible and therefore will have no limitations to their use in all building types or classifications.
One of the most cost effective ways to increase R-value is to simply increase thickness of insulation. Thicker insulation improves R-value. Increasing density of insulation will also improve R-value. The most common method of installation for metal buildings involves placing insulation over roof purlins under metal roof sheets, including side cladding. The roof sheets are normally installed concurrently with the insulation in one operation. To find out more about installation systems and the products used, be sure to visit Isover. Be sure to consult with your insulation specialist who will assist in providing the best cost effective solution for your specific energy efficient building requirements.
If you consider that the building sector accounts for more than 50% of the energy consumption in South Africa, it quickly becomes clear what a critical role insulation plays. But this insulation needs to be correctly installed, with the know-how of industry experts who can guide you every step of the way. It’s time to make a dent in that shockingly high 50% once and for all.
Acknowledgement and thanks go to Des Schnetler, TIPSASA chairperson; Christopher Knight, sales and marketing, Western Cape, at Rigifoam; and Ben de Freitas, Commercial and Technical Consultant, at Isover for the information contained in this article.